Anharmonicity of zone-centre optical phonons: Raman spectra of the isomorphous alpha-quartz, berlinite and gallium phosphate in the temperature range8-300 K
R. Ouillon et al., Anharmonicity of zone-centre optical phonons: Raman spectra of the isomorphous alpha-quartz, berlinite and gallium phosphate in the temperature range8-300 K, J RAMAN SP, 31(7), 2000, pp. 605-613
The temperature dependence of the optical-phonon wavenumbers and bandwidths
in the isomorphous alpha-quartz, berlinite (AlPO4) and gallium phosphate (
GaPO4) was investigated by Raman scattering experiments in the temperature
range 8-300 K, Combining these data with those from high-pressure Raman sca
ttering experiments (up to 20 GPa), we estimated the implicit (thermal volu
me expansion) and explicit (pure self-anharmonic) temperature contribution
to the temperature wavenumber shifts observed in isobaric experiments. In t
he framework of the Gruneisen approximation, the mode-Gruneisen parameters
of the A(1) modes in GaPO4 are given. As expected, these results are simila
r to those previously reported for quartz and berlinite, In the temperature
range 8-300 K, which is less than the alpha-beta temperature of transition
(Talpha-->beta approximate to 850 K) of quartz and berlinite, the phonon p
opulation decay processes appear to be the main cause of phonon damping in
the three materials. Copyright (C) 2000 John Wiley & Sons, Ltd.